Airflow management improvement in an aerosol-generating device

ABSTRACT

An aerosol-generating device comprises a vaporization element having an outlet and is configured to vaporize a liquid. An airflow passage extends from the outlet of the vaporization element and is configured to convey vapor to an outlet of the aerosol-generating device. A hot air channel is configured to direct heated air towards the outlet of the vaporization element, and a dilution air channel is configured to direct ambient air into the device and to mix the ambient air with the vapor conveyed in the airflow passage to form an aerosol.

The present invention relates to an aerosol-generating device and in particular to the airflow management in an aerosol-generating device.

Generating an aerosol using an aerosol-generating device is widely known in the art. It is known for example to generate an aerosol with a capillary aerosol-generating device. A capillary aerosol-generating device typically comprises a housing. The housing may comprise a capillary tube, surrounded by heating elements and an aerosol-forming chamber. The capillary tube may be connected to a reservoir holding vaporizable liquid.

Liquid flows through the capillary tube, which is heated until a supersaturated vapor is generated. The supersaturated vapor exits the capillary tube at the outlet of the capillary tube. The supersaturated vapor is mixed with air after it exits the capillary tube. Thereby the supersaturated vapor cools and condenses to produce an aerosol. The outlet of the aerosol-chamber of the capillary aerosol-generating device may be connected to a conveying aerosol tube.

Aerosol generation may pose a challenge during its use, especially for scientific studies, due to insufficiently controlled interaction of supersaturated vapor with air. In particular in capillary aerosol-generating devices this may result in aerosol droplets forming on the internal surface inside the capillary tube or an undesired particle size distribution. Such aerosol droplets can adhere to the internal surface of the capillary tube to function as the center of nucleation, such that the droplets eventually grow in sufficient size that they interfere with the airflow path.

Such unwanted effects not only reduce the net aerosol production but may also affect the results of a scientific study from the production of unwanted and unintended chemical decomposition products.

Therefore, it would be desirable to provide an aerosol-generating device that allows increased control of the aerosol-generating process.

It would be particularly desirable to provide an aerosol-generating device that may be reliably used in scientific studies regarding aerosol generation. For this purpose it would be further desirable to have an aerosol-generating device that offers increased opportunities to control essential parameters of the liquid droplet aerosol formation process.

It would be particularly desirable to provide a capillary aerosol-generating device fulfilling the above objectives.

It would also be desirable to provide a capillary aerosol-generating device that has a housing that does not get too hot during use, such that handling of the device is improved.

In an embodiment of the invention there is provided an aerosol-generating device comprising a vaporization element having an outlet and being configured to vaporize a liquid. The aerosol-generating device further comprises an airflow passage extending from the outlet of the vaporization element and being configured to convey vapor to an outlet of the aerosol-generating device. The aerosol-generating device further comprises a hot air channel that is configured to direct heated air towards the outlet of the vaporization element. The aerosol-generating device also comprises a dilution air channel configured to direct ambient air into the aerosol-generating device and to mix the ambient air with the vapor conveyed in the airflow passage to form an aerosol.

In an embodiment of the invention the outlet of the hot air channel may be concentrically arranged around the outlet of the vaporization element.

The vaporization element may comprise a heater element. The heater element may be an electric heater element. The heater element may be a resistive heater or an inductive heater. The heater element may be a mesh heater or coil heater.

The vaporization element may comprise a wick and coil arrangement. The vaporization element may comprise a mesh heater arrangement.

The air flow passage may convey vapor and aerosol. The expression “vapor” is usually used to refer to a vaporized liquid. The expression “aerosol” is usually used to refer to a gaseous mixture in which a part of the vaporized liquid has condensed and forms liquid droplets suspended in the air flow.

The hot air from the hot air channel may form a “curtain” between the vapor and the aerosol conveyed in the airflow passage and surrounding elements of the aerosol-generating device. In this way the vapor is prevented from contacting colder parts of the aerosol-generating device. Thereby aerosol-formation may be better controlled, since most of the condensation that leads to the formation of aerosol is prevented by the hot air curtain. In addition, premature condensation of the vapor may be largely prevented.

In an embodiment of the invention the aerosol-generating device comprises a vaporization element with a capillary tube. Such aerosol-generating device is also referred to herein as “capillary aerosol-generating device”.

In an embodiment of the invention there is provided a capillary aerosol-generating device comprising a capillary tube having an inlet and an outlet and being configured to convey vaporizable liquid. A heater element is provided in thermal contact with the capillary tube. The capillary aerosol-generating device further comprises a hot air channel that is configured to direct heated air towards the outlet of the capillary tube and to form an aerosol. The capillary aerosol-generating device also comprises a dilution air channel that is configured to direct ambient air into the device and to mix the ambient air with the aerosol.

By directing hot air towards the outlet of the capillary tube the vaporized liquid emerging from the outlet of the capillary tube is prevented from cooling down too quickly. In this way premature aerosol droplet formation in the vicinity of the outlet of the capillary tube or even within the capillary tube is efficiently reduced. Aerosol formation is supported by mixing the aerosol further downstream with ambient air. By adjusting the amount and the temperature of the different air streams, aerosol formation can be influenced to obtain for example a desired particle size distribution.

Moreover, the droplets are prevented from coming into contact with the heating elements. Thus, the risk that carbonyls or other unwanted constituents may be produced is reduced.

Due to the well-controlled aerosol formation, the aerosol-generating device may be advantageously used in scientific studies. Scientific studies may require test equipment which can operate reliably and reproducibly for an extended period of time. Such scientific studies may aim at mimicking a user's aerosol-consumption or may be directed as investigating long-time effects of aerosol consumption.

The outlet of the hot air channel may be arranged such that the hot air stream is routed around the outlet of the capillary tube of a capillary aerosol-generating device. The outlet of the hot air channel may be arranged around the outlet of the capillary tube. Preferably, the outlet of the hot air channel may be concentrically arranged around the outlet of the capillary tube. By routing the hot air stream around the outlet of the capillary tube, the hot air stream may form a cushion that shields the vaporized liquid from contacting any colder parts of the device and thereby prevents the vaporized liquid from condensing at such cooler surfaces.

The aerosol-generating device may comprise a heater module and an aerosol-forming module.

The heater module may comprise a housing, a heater element and a capillary tube in thermal contact with the heater element. The capillary tube may be arranged centrally in the capillary aerosol-generating device. The capillary tube may be configured to receive at its inlet a vaporizable liquid from a liquid reservoir. The capillary tube may be further configured such that the outlet of the capillary tube is in fluid connection with the aerosol-forming module.

The heater module may have a length of between 30 and 40 millimeters. The aerosol-forming module may have a diameter of 20 to 25 millimeters. Preferably, the heater module may have a length of about 30 millimeters and a diameter of 25 millimeters.

The aerosol-forming module may have any suitable construction. The aerosol-forming module may have a generally tubular form. The aerosol-forming module may comprise a housing in which an aerosol-forming chamber and a dilution chamber are defined. The aerosol-forming chamber may be arranged adjacent the upstream end of the aerosol-forming module and the dilution chamber may be arranged downstream from the aerosol-forming chamber. The aerosol-forming module may have an outlet end at which the aerosol may exit the aerosol-generating device.

The aerosol-forming module may have a length of between 40 to 50 millimeters. In capillary aerosol-generating devices the aerosol-forming module may have a larger length. In capillary aerosol-generating devices the aerosol-forming module may have a length of between 1000 and 1500 millimeters. The aerosol-forming module may have a diameter of 20 to 25 millimeters. The aerosol-forming module may preferably have a length of about 1000 millimeters and a diameter of about 25 millimeters.

The heater module and the aerosol-forming module may be formed integrally.

The heater module and the aerosol-forming module may be formed from any suitable material. The heater module and the aerosol-forming module may be formed from glass or polymeric material such as pyrex or plexiglass.

The heater module and the aerosol-forming module may be releasably connected to each other. The releasable connection may be facilitated by any suitable connection means. The releasable connection may be facilitated by a connection element in the form of a front cap. The front cap may be configured of a generally tubular shape. One end of the front cap may be configured to be connected to the heater module. The other end of the front cap may be configured to be connected to the aerosol forming module. The front cap may comprise an opening to facilitate the fluid connection between the heater module and the aerosol-forming module.

The modular construction may have a plurality of beneficial effects. Modules may be changed depending on user preferences. In case of malfunction it is sufficient to replace defective modules, while operable modules may be continued to be used.

The connection element may be formed from polymeric material. The connection element may be formed from polyaryletherketone (PAEK), polyetheretherketone (PEEK), polyetheretherketoneketone (PEEKK) or polytetrafluoroethylene (PTFE).

The connection element may have a length of between 20 and 25 millimeters. The connection element may have a diameter of 25 to 50 millimeters. Preferably the connection element may have a length of about 20 millimeters and a diameter of about 40 millimeters.

The aerosol-generating device may further be configured such that the heated air from the hot air channel is introduced into the aerosol-forming chamber and the ambient air from the dilution air channel is introduced into the dilution chamber.

The capillary tube may be provided centrally in the heater module. The heater element may be arranged in thermal contact around the capillary tube. In this way good thermal contact between the heater element and the capillary tube is ensured. The housing may be arranged around the heater element.

The capillary tube may be made from any suitable inert material. Suitable materials for the capillary tube include glass and titanium.

The capillary tube may have a length of 35 to 45 millimeters and a diameter of up to 2 millimeters. Preferably, the capillary tube may have a length of about 35 millimeters and a diameter of 1 millimeter.

The heater element may be an electric heater element. The heater element may be a resistive or an inductive heater element. The heater element may comprise two half-cylindric heater segments. Each of the half-cylindric segments may comprise two heater segments such that in total the heater element may consist of four heater segments.

The heater element may be controlled by any suitable controller. A thermo-element may be provided for monitoring and controlling the temperature of the heater element.

A pump may be used to deliver the vaporizable liquid to the capillary tube. The pump may be a peristaltic pump.

The hot air channel may be arranged in the heater module. The hot air channel may be arranged in thermal contact with the heater element. The heater element may be used to provide the required heat to generate the hot air. In this way the heater element is used for two purposes at the same time. The heater element is used for providing the necessary heat to vaporize the liquid within the capillary tube. At the same time the heater element may be used to provide the required heat to generate the hot air stream. Such embodiment represents a particularly efficient use of the components of the device. The heater is used for the purpose of heating the liquid and the air to be mixed with the volatilized liquid. An additional heater is not required.

The hot air channel may be arranged radially outward from the heater element. The hot air channel may be arranged radially outward from the heater element and between the heater element and the housing of the heater module. The hot air channel may be provided as an annular channel arranged concentrically around the heater element. The hot air channel may be arranged such as to fully enclose the radial outer surface of the heater element. By arranging the hot air channel in this way, a large contact surface to the heater element is obtained. Such arrangement allows for good thermal contact and fast heat transfer to the hot air stream.

At the same time the hot air channel may act as a heat shield for the housing. In use, the heat generated by the heater element unavoidably travels towards the housing. Thus, the housing tends to get hot during use, which may be uncomfortable for handling of the device. By guiding the hot air stream between the heater element and the housing, the heat is taken up by the hot air stream, preventing the housing from becoming too hot during use.

In embodiments in which the hot air channel is arranged in the heater module, the heater module may comprise an air inlet. In addition, a further opening may be required to guide the hot air stream from the heater module into the aerosol-forming chamber of the aerosol-forming module. For this purpose, the connection element may be configured to establish a fluid connection of the hot air channel to the aerosol-forming chamber.

The connection element may comprise a pinhole inlet via which the hot air channel is fluidly connected to the aerosol-forming chamber. The pinhole inlet of the connection element may be concentrically arranged around the outlet of the capillary tube. The pinhole inlet of the connection element may have a diameter of up to 3 millimeters, and preferably a diameter of about 2 millimeters.

By providing the pinhole inlet concentrically around the outlet of the capillary tube the hot air stream emerges simultaneously with the vapor from the capillary tube into the aerosol-forming chamber of the aerosol-forming module. The hot air stream forms an envelope around the vapor and thereby prevents the vapor from cooling too quickly and condensing or clogging around the opening of the capillary tube.

The hot air channel may also be arranged in the aerosol-forming module, only. In such embodiments, the heated air is generated by another heater element, for example by an external heater. The aerosol-forming module comprises a first air inlet for introducing the externally heated air. The hot air stream is then guided within the aerosol-forming module towards the exit of the capillary tube. For this purpose the aerosol-forming module may comprise a first tubular element. The inner volume of the first tubular element may define the aerosol-forming chamber. The first tubular element may be arranged centrally within the aerosol-forming chamber. An annular space between the first tubular element and the housing of the aerosol-forming module may define the hot air channel that guides the hot air from the first air inlet towards the exit of the capillary tube. The outlet of the hot air channel may be formed such that the hot air stream again forms an envelope for the vapor leaving the capillary tube.

The hot air may be heated up to between 50 and 250 degrees Celsius. The hot air may be heated up to between 50 and 180 degrees Celsius.

The dilution air channel may be arranged in the aerosol-forming module of the aerosol-generating device. The dilution air channel is configured to direct cold, ambient air into the device and to mix the ambient air with the aerosol. The cold air stream may be directed into the dilution chamber. The cold air stream may be mixed in the dilution chamber with the aerosol generated in the upstream aerosol-forming chamber. By mixing the aerosol with the ambient air the aerosol enhances its volume. The resulting diluted aerosol flows onwards to an air outlet of the aerosol-generating device with no or substantially reduced condensation of aerosol on the internal surfaces of the aerosol-forming module.

The ambient air may be cold air. The ambient air may be conditioned before mixing with the aerosol. Conditioning the ambient air may include adjusting relative humidity, temperature and filtering. The ambient air may be conditioned to any temperature between −25 and 80 degrees Celsius. The ambient air may be process air with a temperature of about 22 degrees Celsius. The ambient air may be heap-filtered process air with a temperature of about 22 degrees Celsius and a relative humidity of about 60 percent.

The aerosol-forming module may comprise a cold air inlet. The dilution air channel may extend from the cold air inlet to the dilution chamber. The dilution air channel may be formed in an annular space between a second tubular element and the housing of the aerosol-forming module. The second tubular element may be formed integrally with and in extension of the first tubular element.

The first and second tubular elements may have a combined total length of 500 to 800 millimeters and may preferably have a length of about 700 millimeters.

Air supplies for the air inlets of the aerosol-generating device may be provided as volume controlled air flow supplies. Air supplies may comprise pressurized (synthetic) air. The air supplies may be configured to provide, humidity adjusted, temperature conditioned and (hepa-) filtered process air. By using volume and pressure controlled process air a potential air backflow is avoided.

Below, there is provided a non-exhaustive list of non-limiting examples. Any one or more of the features of these examples may be combined with any one or more features of another example, embodiment, or aspect described herein.

Example A: Aerosol-generating device comprising a vaporization element having an outlet and being configured to vaporize a liquid, an airflow passage extending from the outlet of the vaporization element and being configured to convey vapor to an outlet of the aerosol-generating device, a hot air channel configured to direct heated air towards the outlet of the vaporization element, and a dilution air channel configured to direct ambient air into the device and to mix the ambient air with the vapor conveyed in the airflow passage to form an aerosol.

Example B: Aerosol-generating device according to example A, wherein the outlet of the hot air channel is concentrically arranged around the outlet of the vaporization element.

Example C: Aerosol-generation device according to example A or B, wherein the vaporization element comprises a capillary tube and a heater element, wherein the capillary tube has an inlet and an outlet and is configured to convey vaporizable liquid, and wherein the heater element is in thermal contact with the capillary tube.

Example D: Aerosol-generating device according to any one of the preceding examples, wherein the aerosol-generating device comprises a heater module and an aerosol-forming module that are connected to each other.

Example E: Aerosol-generating device according to any one of the preceding examples, wherein the heater module and the aerosol-forming module are connected by a connection element.

Example F: Aerosol-generating device according to any one of the preceding examples, wherein the aerosol-forming module comprises an aerosol-forming chamber and a dilution chamber.

Example G: Aerosol-generating device according to any one of the preceding examples, wherein the aerosol-forming chamber is arranged adjacent the upstream end of the aerosol-forming module and the dilution chamber is arranged downstream from the aerosol-forming chamber.

Example H: Aerosol-generating device according to any one of the preceding examples, wherein the heated air from the hot air channel is introduced into the aerosol-forming chamber and the ambient air from the dilution air channel is introduced into the dilution chamber.

Example I: Aerosol-generating device according to any one of examples C to H, wherein the hot air channel is arranged in thermal contact with the heater element.

Example J: Aerosol-generating device according to example I, wherein the heater element is arranged around the centrally arranged capillary tube and the hot air channel is arranged radially outward from the heater element.

Example K: Aerosol-generating device according to any one of examples I and J, wherein the connection element comprises a pinhole inlet via which the hot air channel is fluidly connected to the aerosol-forming chamber.

Example L: Aerosol-generating device according to any one of examples I to K, wherein the pinhole inlet of the connection element is concentrically arranged around the outlet of the capillary tube.

Example M: Aerosol-generating device according to any one of the preceding examples, wherein the hot air channel is arranged in the aerosol-forming module and the heated air is generated by an external heater.

Example N: Aerosol-generating device according to any one of the preceding examples, wherein the aerosol-forming module comprises a centrally arranged tube, wherein the inner volume of that tube defines the aerosol-forming chamber.

Example O: Aerosol-generating device according to any one of the preceding examples, wherein the air channels in the aerosol-forming module are defined between the outer surface of the tube and the inner surface of the housing.

Example P: Aerosol-generating device according to any one of examples C to O, wherein the capillary tube is arranged centrally in the capillary aerosol-generating device and is arranged to receive vaporizable liquid from a reservoir.

Example Q: Aerosol-generating device according to any one of examples C to P, wherein a pump is used to deliver the vaporizable liquid to the capillary tube.

Example R: Aerosol-generating device according to any one of examples C to Q, wherein the heater element comprises two half-cylindric heater segments, which each comprise two further heater segments.

Example S: Aerosol-generating device according to any one of examples C to R, further comprising a thermoelement for monitoring the temperature of the heater element.

Features described in relation to one embodiment may equally be applied to other embodiments of the invention.

The invention will be further described, by way of example only, with reference to the accompanying drawings in which:

FIG. 1 shows a capillary aerosol-generating device according to the present invention;

FIG. 2 shows a modified capillary aerosol-generating device;

FIG. 3 schematically illustrates air flow management in the device of FIG. 2 ;

FIG. 4 shows a modification of the capillary aerosol-generating device of FIG. 2 .

FIG. 1 depicts a first embodiment of a capillary aerosol-generating device 10 according to the present invention. The capillary aerosol-generating device 10 comprises a heater module 12 and an aerosol-forming module 14, which are connected to each other using a connection element in the form of a front cap 16.

The heater module 12 comprises a generally cylindric housing 20, a heater element 22 and a capillary tube 24. The capillary tube 24 is provided centrally in the heater module 12 and is surrounded by and in thermal contact with the heater element 22. The heater element 22 comprises two half-cylindric heater segments 22 a, 22 b, which each comprise two further heater segments.

The capillary tube 24 is in fluid communication with a liquid reservoir (not shown). In FIG. 1 the capillary tube 24 receives the aerosolizable liquid from the liquid reservoir via a tubing 26. A peristaltic pump (not shown) may be used to pump the liquid into the capillary tube 24. The aerosolizable liquid is pumped through the capillary tube 24 and is heated by the thermal energy provided from the heater element 22. Upon heating the aerosolizable liquid is formed into supersaturated vapor or hot aerosol.

The heater module 12 may also comprise one or more thermocouples (not shown) in order to monitor the temperature generated by the heater element 22. The measured temperature may be used as feedback to control the energy provided to the heater element 22.

The heater module 12 is connected to the aerosol-forming module 14 by front cap 16. The front cap 16 is a generally tubular element that has a threading 30, 32 on either end. The threading 30 at the upstream end is used to connect the front cap 16 to the heater module 12. The threading 32 at the downstream end is used to connect the front cap 16 to the aerosol-forming module 14. The front cap 16 has a central opening 18 through which the capillary tube 24 extends. When the capillary aerosol-generating device 10 is fully assembled the outlet 28 of the capillary tube 24 is located such that the vaporized liquid is discharged into an aerosol-forming chamber 42 of the aerosol-forming module 14.

The aerosol-forming module 14 of the capillary aerosol-generating device 10 comprises a housing 40 with air inlets 44, 46, a first tubular element 48 a and a second tubular element 48 b. In the embodiment of FIG. 1 the first and second tubular elements 48 a, 48 b are integrally formed.

The aerosol-forming module 14 comprises a first air inlet 44 for introducing hot air. The hot air is created by using an external heater (not shown). The hot air stream is guided via an annular hot air channel 50 from the hot air inlet 44 of the aerosol-forming module 14 towards the exit 28 of the capillary tube 24. The hot air channel 50 is formed in the annular space between the first tubular element 48 a and the housing 40 of the aerosol-forming module 14. The outlet of the hot air channel 50 is concentrically arranged around the outlet 28 of the capillary tube 24. In this way the hot air stream discharged from the hot air channel 50 forms an envelope for the supersaturated vapor leaving the capillary tube 24.

The inner volume of the first tubular element 48 a defines the aerosol-forming chamber 42 into which the supersaturated vapor and the hot air stream is discharged.

The aerosol-forming module 14 comprises a second air inlet 46 for introducing cold ambient air. The cold air stream is guided via a dilution air channel 52 from the cold air inlet 46 of the aerosol-forming module towards the dilution chamber 43. The dilution air channel 52 is formed in the annular space between the second tubular element 48 b and the housing 40 of the aerosol-forming module 14. In a dilution chamber 43 the cold air stream is mixed with the aerosol formed in the aerosol-forming chamber 42. The resulting diluted aerosol flows onwards to an aerosol outlet 54 of the capillary aerosol-generating device 10.

FIG. 2 shows a further embodiment of a capillary aerosol-generating device 10 according to the present invention. The capillary aerosol-generating device 10 comprises a heater module 12 and an aerosol-forming module 14, which are connected to each other using a front cap 16.

In this embodiment the aerosol-forming module 14 only comprises one air inlet 46 which corresponds to the cold air inlet 46 of the first embodiment. Cold ambient air is guided via the dilution air channel 52 into the dilution chamber 43 to be mixed therein with the aerosol.

In this embodiment the annular hot air channel 50 is comprised in the heater module 12 and is formed in the annular space between the heater element 22 and the housing 20 of the heater module 12. The heater module 12 comprises an air inlet 56. Air introduced via this air inlet 56 is guided along the hot air channel 50. The hot air channel 50 is in thermal contact with the heater element 22 such that the air guided in the hot air channel 50 is heated up by the thermal energy from the heater element 22.

Also in this embodiment, the heater module 12 and the aerosol-forming module 14 are connected via a threaded front cap 16. The front cap 16 has substantially the same form as the front cap 16 described with FIG. 1 . However, the front cap 16 of FIG. 2 is additionally configured to fluidly connect the hot air channel 50 and the aerosol-forming chamber 42 of the aerosol-forming module 14. For this purpose, the central opening 18 in the front cap 16 has an inner diameter that is larger than the outer diameter of the capillary tube 24. The hot air stream from the hot air channel 50 is passed concentrically with the capillary tube 24 through the opening 18 of the front cap 16.

The air management in this embodiment is schematically depicted in FIG. 3 . Capillary tube 24 extends from the heater module 12 through the opening 18 into the aerosol-forming chamber 42 of the aerosol-forming module 14. The supersaturated vapor is discharged from the outlet end 28 of capillary tube 24 into the aerosol-forming chamber 42. Simultaneously the hot air stream from the hot air channel 50 is guided through the annular slit between the capillary tube 24 and the wall 18 a of the front cap 16 and is also discharged into the aerosol-chamber 42 of the aerosol-forming module 14. The hot air stream forms an envelope for the supersaturated liquid such that premature condensation is prevented. The outer diameter of the capillary tube 24 amounts to about 1 millimeter. The inner diameter of the opening 18 in the front cap 16 amounts to about 2 millimeters.

FIG. 4 shows a modification of the embodiment depicted in FIG. 2 .

Again, the hot air channel 56 is comprised in the heater module 12 and the hot air flow is managed as illustrated with FIG. 3 . In this embodiment the dilution air channel 52 has two outlets 58, 60. The first outlet 58 corresponds to the outlet as described with FIG. 2 and discharges the cold air stream into the dilution chamber 43 of the aerosol-forming module 14. An additional cold air outlet 60 is formed in the vicinity of the outlet end 28 of the capillary tube 24. This outlet 60 is formed concentrically with the outlet 28 of the capillary tube 24 and also concentrically with the opening 18. By admixing cold air in the aerosol-forming chamber 42 a desired shaping of the resulting aerosol may be obtained. 

1. Aerosol-generating device comprising a vaporization element having an outlet and being configured to vaporize a liquid, an airflow passage extending from the outlet of the vaporization element and being configured to convey vapor to an outlet of the aerosol-generating device, a hot air channel configured to direct heated air towards the outlet of the vaporization element, and a dilution air channel configured to direct ambient air into the device and to mix the ambient air with the vapor conveyed in the airflow passage to form an aerosol.
 2. Aerosol-generating device according to claim 1, wherein the outlet of the hot air channel is concentrically arranged around the outlet of the vaporization element.
 3. Aerosol-generation device according to claim 1, wherein the vaporization element comprises a capillary tube and a heater element, wherein the capillary tube has an inlet and an outlet and is configured to convey vaporizable liquid, and wherein the heater element is in thermal contact with the capillary tube.
 4. Aerosol-generating device according to claim 1, wherein the aerosol-generating device comprises a heater module and an aerosol-forming module that are connected to each other.
 5. Aerosol-generating device according to claim 1, wherein the heater module and the aerosol-forming module are connected by a connection element.
 6. Aerosol-generating device according to claim 1, wherein the aerosol-forming module comprises an aerosol-forming chamber and a dilution chamber.
 7. Aerosol-generating device according to claim 1, wherein the aerosol-forming chamber is arranged adjacent the upstream end of the aerosol-forming module and the dilution chamber is arranged downstream from the aerosol-forming chamber.
 8. Aerosol-generating device according to claim 1, wherein the heated air from the hot air channel is introduced into the aerosol-forming chamber and the ambient air from the dilution air channel is introduced into the dilution chamber.
 9. Aerosol-generating device according to claim 3, wherein the hot air channel is arranged in thermal contact with the heater element.
 10. Aerosol-generating device according to claim 9, wherein the heater element is arranged around the centrally arranged capillary tube and the hot air channel is arranged radially outward from the heater element.
 11. Aerosol-generating device according to claim 9, wherein the connection element comprises a pinhole inlet via which the hot air channel is fluidly connected to the aerosol-forming chamber.
 12. Aerosol-generating device according to claim 9, wherein the pinhole inlet of the connection element is concentrically arranged around the outlet of the capillary tube.
 13. Aerosol-generating device according to claim 1, wherein the hot air channel is arranged in the aerosol-forming module and the heated air is generated by an external heater.
 14. Aerosol-generating device according to claim 1, wherein the aerosol-forming module comprises a centrally arranged tube, wherein the inner volume of that tube defines the aerosol-forming chamber.
 15. Aerosol-generating device according to claim 1, wherein the air channels in the aerosol-forming module are defined between the outer surface of the tube and the inner surface of the housing. 